Fifth wheel activated trailer steering

Abstract

Steering mechanism for trailer wheels is provided with a slide having a tongue selectively engaged with and retracted from the fifth wheel of a tractor. When the tongue is engaged with the fifth wheel, any pivoting of the fifth wheel about the kingpin connection between the tractor and trailer, as when the tractor is steered from a straight ahead position relative to the trailer, causes the tongue to swing a link pivoted on the slide mechanism under the trailer. This swinging of the link drives a flexible cable to control a valve of a power steering system for the trailer rear wheels. The components are mounted under the floor of the trailer and a cable driven winch with a crank or power drive at the side of the trailer advances and retracts the slide to move the tongue into and out of engagement with the tractor fifth wheel. Magnets are mounted in the tongue and a torsion spring is provided in the winch mechanism to maintain tight contact between the tongue and fifth wheel. An adjustable lost motion linkage may control the power steering valve for preventing sudden swing-out of the extended end portion of the trailer. The mechanism greatly reduces the turning radius for the vehicle, prevents turnover in the event of sudden acceleration, swerving and sudden turns, and improves the tracking of the trailer.

I claim as my invention: 
     
       1. A power steering system for trailers of the type having steerable rear trailer wheels and a front coupling pin for coupling to and uncoupling from a tractor having a slotted fifth wheel with a slot receiving the coupling pin of the trailer which comprises, a slide mounted under the trailer for fore and aft movement, a link having a rear end pivotally mounted on said slide and a front end swingable laterally about the pivoted rear end, a tongue pivoted on the front end of the link shaped to fit the slot of the tractor fifth wheel, means driving the slide to move the tongue into and out of said slot of the fifth wheel, said tongue when seated in said slot of the fifth wheel swinging said link laterally as the tractor turns relative to the trailer, a power steering assembly on said trailer for said steerable rear trailer wheels, a power steering valve controlling said power steering assembly, and means connecting said link with said power steering valve to effect steering of said steerable rear trailer wheels with the tractor as the tractor is turned relative to the trailer. 
     
     
       2. In a tractor-semi trailer vehicle of the type having a tractor with a slotted fifth wheel, a trailer with steerable rear wheels and a trailer kingpin selectively coupled to said slotted fifth wheel of the tractor, the improvement of a tongue mounted on the trailer fitting the slot of the fifth wheel to rotate with the fifth wheel about the trailer kingpin, means on the trailer advancing the tongue into the fifth wheel slot and retracting the tongue out of the slot and under the trailer, a power steering system for said steerable rear wheels of the trailer including a pressured hydraulic liquid source and a valve controlling the hydraulic liquid to power the steering of said steerable rear wheels, and means actuated by said tongue operating said valve, said power steering system capable of being selectively coupled and uncoupled by said advancing and retracting of said tongue while said tractor remains in coupling engagement with said trailer. 
     
     
       3. A tractor fifth wheel actuated trailer steering system which comprises in combination with a tractor having a fifth wheel and a trailer having steerable wheels, a slide mounted for fore and aft movement under the trailer, a forwardly projecting link swingably mounted on said slide and having a front end, a tongue pivotally mounted on the front end of said link arranged to be selectively coupled with the tractor fifth wheel to swing the link laterally as the fifth wheel turns, a power steering system including a power steering valve on the trailer for turning the steerable wheels of the trailer, and a flexible drive coupling connecting said link and said valve to operate the power steering system for turning the steerable trailer wheels with the turning of the tractor fifth wheel. 
     
     
       4. A trailer mounted power steering system for a trailer having steerable rear wheels and a tractor having steering wheels and a slotted fifth wheel for coupling from and uncoupling to the trailer which comprises a mechanism slidably mounted under the trailer for selective uncoupling from and coupling to the fifth wheel of the tractor, and a power steering system on the trailer controlled by said mechanism for steering the steerable rear wheels of the trailer simultaneously with the steering of the tractor steering wheels, said power steering system capable of being selectively coupled and uncoupled by advancing and retracting said mechanism while said tractor remains in coupling engagement with said trailer. 
     
     
       5. In a power steering system for a semi trailer having steerable rear wheels and a tractor having a fifth wheel for coupling to and uncoupling from the trailer, the improvement of a mechanism carried under the trailer adapted to be extended from uncoupled into coupled engagement with the tractor fifth wheel, and means actuated by said mechanism controlling the power steering system for turning the steerable rear wheels of the trailer as the tractor is turned, said power steering system capable of being selectively coupled and uncoupled by advancing and retracting said mechanism while said tractor remains in coupling engagement with said trailer. 
     
     
       6. The power steering system of claim 1, wherein the means driving the slide is a winch mechanism mounted along the side of the trailer. 
     
     
       7. The power steering system of claim 1, including magnets mounted on the tongue for gripping the fifth wheel. 
     
     
       8. The power steering system of claim 1, wherein the means connecting the link with the power steering valve is a flexible drive shaft. 
     
     
       9. The power steering system of claim 1, including a lost motion connection between the means connecting the link with the power steering valve and the valve. 
     
     
       10. In the tractor semitrailer vehicle of claim 2, the added improvement of spring means urging the tongue into tight contact with the slot of the fifth wheel. 
     
     
       11. In the tractor semitrailer vehicle of claim 10, the further added improvement of magnets carried by the tongue for gripping the slot of the fifth wheel. 
     
     
       12. In the tractor semitrailer vehicle of claim 2, the added improvement of flexible cable means driven by the tongue for actuating said valve. 
     
     
       13. The steering system of claim 3 including a flexible cable connection between said link and said control valve for transmitting swinging movement of the link into rotation of the valve. 
     
     
       14. The system of claim 3 including a torsion spring urging the slide forward to hold the tongue in coupled engagement with the fifth wheel. 
     
     
       15. The system of claim 3 including a winch mechanism mounted along a side of the trailer for driving the slide forward and rearward. 
     
     
       16. The system of claim 4, wherein said mechanism includes a member fitting the slot of the tractor fifth wheel to swing laterally as the fifth wheel is turned with the tractor. 
     
     
       17. The system of claim 4, wherein the mechanism includes means for snugly fitting the slot of the fifth wheel. 
     
     
       18. The system of claim 17, wherein said means for snugly fitting includes magnets. 
     
     
       19. The further improvement of claim 5, which comprises a slide powered from the trailer mounting said mechanism. 
     
     
       20. The further improvement of claim 5, which comprises indicators showing operation of the mechanism.